Question

Assertion (A): A magnet loses its magnetism when heated.

Reason (R): When heated, the molecules gain thermal energy, and the kinetic energy increases. This results in the breaking of a straight line molecular chain.

• A. A and R are true and R is the correct explanation of A.
• B. A and R are true, but R is not the correct explanation of A.
• C. A is true but R is false.
• D. Both A and R are false.

Answer 1

The correct option is A

A and R are true and R is the correct explanation of A.

The explanation for the assertion statement:

1. A magnet loses its magnetism when heated.
2. The magnet loses its magnetism above the Curie temperature.
3. There is a reduction in the magnetism of the magnets when heated because the particles in the magnet start moving faster.
4. This fast movement of the particles misaligns the magnetic domains and reduces magnetism.

The explanation for the reason statement:

1. The magnetic property of a magnet is due to the presence of a straight molecular chain in the object.
2. When a magnet is heated the molecules of the magnet absorb heat and so the kinetic energy of the molecules increases.
3. When the kinetic energy of the molecule increases the straight molecular chain breaks and so the magnet losses its magnetic property.

Hence the correct option is option (A).